P-111. growth hormone dependent binding to a functional hnf-3 site in the rat cyp2c12 gene

O. Laluna, L. Fernández, R. Ahlgren, H. Karlsson, Jan-Ake Gustafsson, A. Mode

Research output: Contribution to journalArticlepeer-review

Abstract

The growth hormone (GH) secretory profile is sexually dimorphic in the rat. This leads to a sex differentiated expression of cytochrome P450 (CYP) GH-target genes in rat liver. The CW2C12 gene is transcriptionally activated by the female GH secretory profile. We have characterized the proximal CYP2C12 promoter (from -247 to -20 bp) with regard to GH dependent protein-DNA interactions using liver nuclear extracts from rats with different GH status. A GH dependent hypersensitive site was detected at -92 bp by in vitro footprinting analysis. The region surrounding this site was further characterized by gel shift analysis. GH dependent binding was observed to an oligonucleotide encompassing the region -52 to -29. This region is homologous to an HNF-3 binding site and was found to bind HNF-3 a, b and g. In addition, GH-dependent binding activity of intermediate mobility to HNF-3a and -3b was detected. The identity of the GH dependent factor(s) is unknown but could be another member of the HNF-3/forkhead family of transcription factors. To investigate whether the CYP2C12/HNF-3 site confers HNF-3 dependent activation transient transfection experiments were performed in. HepG2 and in Cos-7 cells. A -247 bp CYP2C12-luciferase reporter plasmid was cotransfected vita expression plasmid encoding the rat HNF-3 transcription factor a, b or 9. All three HNF-3 forms stimulated reporter gene activity (5-10 fold in HepG2 and 2-4 fold in Cos-7) demonstrating the functionality of the HNF-3 element in the CYP2C12 promoter.

Original languageEnglish (US)
Number of pages1
JournalEndocrinology and Metabolism, Supplement
Volume4
Issue numberA
StatePublished - Jan 1 1997

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Endocrinology

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